126 On the Basaltes of Saxony. 



holds a mean place between argil and basaltes. Like the 

 latter, it often contains crystals of hornblend, but never 

 ohvin or augite ; and always black hexagonal mica, which 

 is rarely found in basaltes, and which serve to distinguish 

 these two rocks when they approach so near to each, other 

 as to be confounded. Wacke often forms strata below those 

 of basaltes. 



Grunstein, on the other hand, generally covers basaltes. 

 It is composed of feldspar and hornblend in distinct grains. 

 It is the Likinstone of the English, and the granitella of the 

 French mineralogists. A comparative analysis of basaltes 

 from StatTa, and whinstone from Salisbury, gave to Dr. 

 Kennedy the same results with a precision worthy of re- 

 mark ; and it is proved, by the experiments of Sir James 

 Hall, that these two rocks liquefy in the same manner, fur- 

 nish by sudden cooling the same kind of glass, and by slow 

 cooling the same stony substance. 



If basaltes covered by grunstein be accurately observed, 

 grains of feldspar appear between grains of amphibolite, 

 and the rock at length assumes the granitoid texture. It 

 was in the Meissner of Hesse that C. Daubuisson observed 

 the most beautiful examples of this transition. He collected, 

 he says, a series of specimens which in regard to the size 

 of the grain present a decreasing progression from the most 

 beautiful grunstein to the best characterized compact ba- 

 saltes. And that it might not be objected that these speci- 

 mens did not belong to the same mass, he chose some in 

 which the granulated part was in the middle of the compact 

 part, and in which they were seen, as it were, to blend into 

 each other. We shall here remark, that the observation in 

 tmestion is exactly the same as that made by Desmarets and 

 Dolomieu on certain kinds of basaltes which they have ex- 

 cluded from the number of volcanic productions. 



On the other hand, if we consider the wacke on which 

 basaltes rests, it will be seen to degenerate below into argil 

 and then into gravel, while above it gradually assumes the 

 colour, the texture, and solidity of basaltes. C. Daubuis- 

 son has seen prisms of basaltes very hard and very compact 

 in its upper extremity, become tender and argillaceous at 

 its lower. Dr. Reuss found in Bohemia basaltes the pris- 

 matic division of which was propagated in the wacke and 

 the argil, which served it as a support. And before these 

 obsenors, so long as fifteen years ago, the celebrated Wer- 

 ner, speaking of the Scheibenberg, said :— i( I have seen, 

 by a progressive series of shades, the most perfect transi- 

 tion of argil into wacke, and of the latter into basaltes, 



These 



